NOAA Forecasters: Red River Will Crest Again in Fargo-Moorhead in Late April

April 3, 2009

Warming temperatures in the Red River of the North basin will begin melting ice and snowpack, setting the stage for a dangerous second crest in Fargo, N.D., and Moorhead, Minn., later this month, according to forecasters with NOAA’s National Weather Service.

After using all available forecast temperature information to assess its impact on the melt of snow and ice that remains in the Red River Basin, the National Weather Service updated the outlook for the second crest at Fargo. The current National Weather Service outlook indicates a high probability (75 percent chance) of reaching or exceeding 41 feet and a 25 percent chance of reaching or exceeding 42.8 feet. This second crest currently is expected to occur in the latter half of April.

Fargo saw a March record rainfall of 4.62 inches, topping the 1882 record of 2.83 inches, and a record March snowfall of 28.1 inches, topping the 1997 record of 26.2 inches. The current winter season (2008-09) snowfall through April 3 at Fargo-Moorhead was second only to 1996-97 totals. Frigid temperatures have kept this water frozen in place, and it will begin to flow into the river system in the coming weeks. Before the record March snowfall, water content in the region’s ice and snowpack was as much as 300 percent above normal.

“The collaborative effort of local, state and federal governments to protect Fargo last week paid off, but Fargo isn’t out of the woods yet,” said Scott Dummer, chief hydrologist of the North Central River Forecast Center. “It’s critical that we plan for the second crest now.”

Several factors create a high potential for additional significant flooding in the Red River of the North basin. These factors include:

High flows. Local river levels have fallen after their recent record flows, but these drops are slowed by excessive downstream waters and the overall low-relief of the river valley, leaving a significant amount of water in the river.

Saturated and/or frozen soils. Heavy rain last fall produced saturated soils before winter freeze-up. These soils remain saturated and/or frozen to a depth of 30 inches or more, causing any spring rains or snowmelt to rapidly runoff into the river.

Widespread frozen surface water. Cold temperatures caused overland flow and local runoff to freeze on area fields. This water will quickly become runoff when the temperatures warm above freezing.

Record precipitation and recent significant snowfall. Fargo saw all-time record precipitation over the past seven months, with significant precipitation throughout the basin, particularly upstream of Fargo. The recent March 30-April 1 snow storm brought an additional 10-20 inches of snow across broad sections of the basin, which will increase runoff into the river when melting begins.

Reduced water storage. Area reservoirs are virtually full and currently have little or no additional storage capacity. Officials are releasing water from these reservoirs. Additional runoff will enhance the need for further releases.

Spring warming. An inevitable warm-up through the spring combined with the threat of additional rainfall could exacerbate the potential for rapid runoff.

Concerns still remain about the first flood wave as it continues to slowly move downstream toward Drayton. Residents can monitor local conditions online.

NOAA urges residents of Fargo-Moorhead and Red River Valley communities to continue heeding orders issued by local officials. If told to evacuate, do so immediately.

NOAA understands and predicts changes in the Earth’s environment, from the depths of the ocean to the surface of the sun, and conserves and manages our coastal and marine resources.